nginx 1.1.8 *) Change: the ngx_http_limit_zone_module was renamed to the ngx_http_limit_conn_module. *) Change: the "limit_zone" directive was superseded by the "limit_conn_zone" directive with a new syntax. *) Feature: support for multiple "limit_conn" limits on the same level. *) Feature: the "image_filter_sharpen" directive. *) Bugfix: a segmentation fault might occur in a worker process if resolver got a big DNS response. Thanks to Ben Hawkes. *) Bugfix: in cache key calculation if internal MD5 implementation was used; the bug had appeared in 1.0.4. *) Bugfix: the "If-Modified-Since", "If-Range", etc. client request header lines might be passed to backend while caching; or not passed without caching if caching was enabled in another part of the configuration. *) Bugfix: the module ngx_http_mp4_module sent incorrect "Content-Length" response header line if the "start" argument was used. Thanks to Piotr Sikora.

/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>


void
ngx_spinlock(ngx_atomic_t *lock, ngx_atomic_int_t value, ngx_uint_t spin)
{

#if (NGX_HAVE_ATOMIC_OPS)

    ngx_uint_t  i, n;

    for ( ;; ) {

        if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) {
            return;
        }

        if (ngx_ncpu > 1) {

            for (n = 1; n < spin; n <<= 1) {

                for (i = 0; i < n; i++) {
                    ngx_cpu_pause();
                }

                if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) {
                    return;
                }
            }
        }

        ngx_sched_yield();
    }

#else

#if (NGX_THREADS)

#error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !

#endif

#endif

}